books.google.co.uk - Originally published in 2003, Perilous Planet Earth places our concern about the threat to Earth from asteroids and comets within an historical context, looking at the evidence for past events within the geological and historical records. The book looks at the way in which prevailing views about modes...https://books.google.co.uk/books/about/Perilous_Planet_Earth.html?id=QuvQQFF6wIcC&utm_source=gb-gplus-sharePerilous Planet Earth